1. Field of the Invention
This invention relates to a process and to apparatus for reacting a thin film of an organic liquid with a gaseous medium under reduced pressure. In particular this invention relates to a process and apparatus for continuously reacting a sulfonatable or sulfatable organic liquid with sulfur trioxide.
2. Description of the Prior Art
In recent years several processes and several types of apparatus have been suggested for reacting thin films of sulfonatable and sulfatable organic liquids with sulfur trioxide. Hereinafter when reference is made to sulfonation processes and to sulfonatable materials, it is to be understood that sulfation processes and sulfatable materials are also included, where their inclusion is applicable.
As the need for developing more forms of energy has grown, sources of oil, once considered too difficult or uneconomical to recover have now assumed much greater importance. This fact has now provided great impetus for improving sulfonating processes and apparatus, for large quantities of sulfonated oil detergents are now used in the "tertiary" oil treatment for the recovery of residual oil from the ground, as can be obtained, for example, from otherwise exhausted oil wells.
This technique, also known as the "Marathon Process" is presently employed to recover some of the vast amount of oil still remaining in the ground. The process involves the use of large quantities of oil-soluble detergents for solubilizing oil remaining in the ground which has not been attainable by the methods used in the past.
But there are also many other uses for sulfonated organics, and whereas color is unimportant when sulfonated oil detergents are employed for oil recovery, the lack of color becomes important in the manufacture of detergents and surface active agents from alkyl aryl hydrocarbons or aliphatic alcohols. Where the final product is designed for household use, a colorless or substantially colorless product is of prime importance.
Sulfonation with sulfur trioxide has advantages over sulfonation procedures using oleum, but the reaction between sulfur trioxide and sulfonatable organic compounds is generally violent and difficult to control. The uncontrolled exothermic reaction provides an undesirable colored product, hence various means to control the reaction have been suggested.
Some of the suggested processes require large quantities of an inert carrier gas such as air, introduced at high velocities to move a thin film of organic liquid along a cooled surface during the reaction. Such processes require air compressors and dryers, becoming costly both because of equipment and power requirements.
A process and apparatus for reacting a thin film of an organic liquid with a gaseous reactant which minimizes the problems discussed above is described in U.S. Pat. Nos. 3,902,857 filed on Aug. 13, 1973, and 4,163,751, a division of the above, filed on Aug. 7, 1979. Another such process is disclosed in U.S. patent application, Ser. No. 285,382 filed Aug. 30, 1972, now abandoned.
It would be desirable, however, to provide an improved process and apparatus for reacting a thin film of an organic liquid with a gaseous sulfur trioxide in a manner to increase production, reduce the cost of operation, reduce the amount of plant space required and provide a high quality substantially colorless product. It would be desirable to provide a sulfonating apparatus so compact as to be readily constructed as a mobile unit, capable of movement to any location where a continuing supply of a sulfonated product is required. Further, it would be desirable to provide such a compact unit capable of still higher production rates in those instances where product color is of secondary importance.